There are a variety of different interfaces for connecting peripheral devices to a host device such as a personal computer (PC), general purpose computer, notebook, laptop, handheld or tablet. PC, for example. ExpressCard™ and its predecessor the PC Card™ interface, both standardized by the Personal Computer Memory Card International Association (PCMCIA) have been employed for interconnecting peripheral devices, for example, for wireless modems, hard disk or solid-state drives, memory or memory card readers, interface adapter cards, tuners or other peripheral devices, to a host device.
The ExpressCard™ interface is physically different from its predecessor, the PC Card™ interface, and has different electrical supply voltage and current limitations. The ExpressCard™ interface standard defines that up to 1.2 A can be provided or drawn at 3.3 V, whereas a PC Card™ compliant device can provide 1.0 A at 3.3 V. ExpressCard™ and PC Card™ standards, furthermore, allow the supply voltage to vary typically between 3.0 V and 3.6 V.
The PC Card™ interface uses a connection to parallel buses including the Industry Standard Architecture (ISA) 16-bit interface or the Peripheral Component Interconnect (PCI) interface, also known in the art as CardBus. The ExpressCard™ interface, however, can use the PCI Express or Universal Serial Bus (USB) serial interfaces. The PC Card™ interface uses a 68-contact pin and socket connector, while the ExpressCard™ interface utilizes a 26-contact beam on blade connector. For example, FIG. 1 illustrates a Pin Out diagram for a prior art ExpressCard™ interface. Because of the nature of the interfaces, signal exchange between PC Card™ and ExpressCard™ interfaces requires at least some form of signal conversion.
Devices, often referred to as adaptors or converters, for connecting peripheral devices with ExpressCard™ interfaces to a host device with a PC Card™ interface are available. However, peripheral devices with an ExpressCard™ interface may draw more than 1.0 A and may therefore, when used with a converter, overload the power supply capabilities of a PC Card™ host interface. This problem may be further aggravated by peripheral devices that stabilize input supply voltage, for example, by using, a switching power converter or inline voltage stabilizer, which in turn may increase the current drawn from the host device in response to a drop in the supply voltage. If the supply current exceeds a predetermined limit, the host device may limit the voltage and/or current supplied to the peripheral device, which may compromise the functionality of the peripheral device, or the host device may drop power supply to the peripheral device completely.
Therefore there is a need for a solution that overcomes one or more of the deficiencies in the art.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.